Радиационная и пожарная опасность натриевого теплоносителя

Abstract

Introduction. Nuclear power plants in the Russian Federation produce about 20 % of the total electricity. On the basis of fast neutron reactors using sodium as a coolant, Rosatom State Corporation is implementing the “Breakthrough” project aimed at the implementation of a nuclear fuel cycle using the energy potential of natural uranium. Study and generalization of information about fire and radiation hazards of sodium coolant is an urgent task to ensure safety in the operation of this type of reactors. Goals and objectives. The purpose of the article is an analytical study of information about sodium coolant radiation and fire hazard, published in domestic and foreign scientific literature. To achieve it, an analysis of fast neutron reactors operating in the world was carried out, the coolants used in fast reactors were considered. System analysis of radionuclides present in sodium coolant has been carried out, comparative diagrams according to radionuclide radiation properties are presented, the most dangerous radionuclides for humans present in the sodium coolant have been identified. The fire hazard of sodium metal and peculiarities of extinguishing fires associated with the leakage of sodium coolant in the primary and secondary circuits of the reactor plant are analyzed. Results and its discussion. At the present time, there is 1 experimental-industrial fast neutron reactor in operation in the world, located in Russia, and 1 experimental reactor in India and China. Sodium is used as a coolant in these reactors. As a result of the literature analysis from open sources, it was found that the main sources of impurities in the metal coolant are protective gas, structural and technological materials of the installation, and products of nuclear reactions. A systematic analysis of the properties of radionuclides present in the metal coolant made it possible to determine the most dangerous of them for human life and health. The fire hazard of sodium coolant is mainly due to its chemical activity. The main ways of extinguishing spilled sodium is isolation from oxygen by covering the puddle of metallic sodium with powdered fire-extinguishing MHS, powdered aluminum oxide or reduction of oxygen concentration in the air below 4 % by volume gas extinguishing with nitrogen, carbon dioxide or inert gases. Conclusions. As a result of the analysis of radionuclides present in the sodium coolant of a fast neutron reactor, it was found that the most dangerous for people are 24Na, 137Cs, 125Sb, 22Na, 239Pu, 54Mn, 110mAg, 131I. Based on the results of the analysis of the fire hazard of radioactive sodium, the most common fire extinguishing agents are established and the features of extinguishing fires that occur when a sodium coolant ignites are described.